This invention relates to intruder resistant shields and more particularly to composite layer intruder resistant shields.
Sensitive areas such as message centers, security offices, weapons storage areas, reaction force quarters, safes, etc., require special security measures against intruders.
Conventional armor and safe materials, such as hardened steel, provide good protection against mechanical cutting devices such as power drills, saws, files, and grinding wheels. However, these materials are very vulnerable to certain conventional fire cutting devices such as oxy-acetylene torches, oxygen lances as well as the pyrotechnic devices like, e.g., pyronol torches. (Examples of pyronol and pyronol torches can be found in U.S. Pat. Nos. 3,503,841; 3,695,951; 3,713,636; and 3,890,174). The pyronol torch contains a powder mixture of nickel, aluminum, ferric oxide, and fluorocarbon (Teflon.TM.), which is pelletized into a cylinderical configuration and placed into a chamber in the torch. After initiation, exothermic reaction takes place inside the torch chamber, and the molten products of the reaction are ejected at high velocity by internally generated gas pressure through a graphite nozzle. The resulting high velocity liquid metal jet has perforated aluminum, magnesium, steel, titanium, and depleted uranium plates ranging in thickness from 0.5 cm to 7.6 cm in about 0.2 seconds. Moreover, the pyronol torches have now been fabricated into hand-held devices which are very easy to use. Clearly these devices present a new security threat which must be met.
As a practical matter, weight and thickness limitations must also be considered. Thus, brute force counter measures such as using thicker steel or concrete may not be available. This is particularly true where a conventional room is to be made secure. Additionally, such a brute force approach would be costly.
Therefore, it would be desirable to provide light weight, inexpensive shielding which provide more protection against burn bars, oxygen lances, oxy-acetylene torches or pyronol or other high velocity molten metal jets. At the same time the shielding must still provide protection against the mechanical cutting devices (power drills, saws, files, and grinding wheels).